Kaka is crucial to Brazil's hopes of a sixth World Cup crown, according to team-mate Robinho.
The Real Madrid star is still trying to recover full fitness following a season disrupted by groin and thigh problems and was replaced by Nilmar in the 78th minute of Brazil's opening 2-1 win over North Korea
But Robinho has no doubt that he remains an important figure for Brazil and told globoesporte.com: "When Kaka plays well he can decide any game. He is very important to us. I realise that we can all improve in the coming games. It was only the first one and what happened was fairly normal."
He added: "The Selecao has excellent players and if we have to replace anyone we are reassured by the quality we have."